Simple Interest
Math MCQs

Question :    Calculate the amount due if James borrowed a sum of $3000 at 6% simple interest for 3 years.

Correct Answer  $3540

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 6%

Time (t) = 3 years

Thus, Amount (A) = ?

The Rate of Interest is always calculated per annum, i.e. per year.

Thus, here 6% simple interest means, Rate of Simple Interest (SI) is 6% per annum.

Method (1) Using Formula

Calculation of Simple Interest

Formula to Calculate Simple Interest

Simple Interest (SI) = Principal × Rate × Time

Thus, Simple Interest (SI) = $3000 × 6% × 3

= $3000 ×⁶/₁₀₀ × 3

= ^{3000 × 6 × 3}/₁₀₀

= ^{18000 × 3}/₁₀₀

= ⁵⁴⁰⁰⁰/₁₀₀

= $540

Thus, Simple Interest = $540

Calculation of Amount

The total money paid to the lender by a borrower is called the Amount.

In other words, sum of priciple and interest is called the Amount.

Formula to Calculate the Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $540

= $3540

Thus, Amount to be paid = $3540 Answer

Method (2)

Calculation of Amount when Principal, Rate of Simple Interest and Time are given

Calculation of Amount directly using Principal, SI, and Time

Formula to calculate the Amount

Amount (A) = Principal (P) + Principal(P) × Rate of Interest (SI) × Time (t)

⇒ A = P + PRT

Here in the question, P = $3000

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 3 years

Thus, Amount (A)

= $3000 + ($3000 × 6% × 3)

= $3000 + ($3000 ×⁶/₁₀₀ × 3)

= $3000 + (^{3000 × 6 × 3}/₁₀₀)

= $3000 + (^{18000 × 3}/₁₀₀)

= $3000 + (⁵⁴⁰⁰⁰/₁₀₀)

= $3000 + $540 = $3540

Thus, Amount (A) to be paid = $3540 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 6%

This, means, $6 per $100 per year

∵ For $100, the simple interest for 1 year = $6

∴ For $1, the simple interest for 1 year = ⁶/₁₀₀

∴ For $3000, the simple interest in 1 year

= ⁶/₁₀₀ × 3000

= ^{6 × 3000}/₁₀₀

= ¹⁸⁰⁰⁰/₁₀₀ = $180

Thus, simple interest for 1 year = $180

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $180 × 3 = $540

Thus, Simple Interest (SI) = $540

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $540

= $3540

Thus, Amount to be paid = $3540 Answer

Similar Questions

(1) In how much time a principal of $3100 will amount to $3286 at a simple interest of 3% per annum?

(2) If Betty paid $4590 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(3) Calculate the amount due after 10 years if Robert borrowed a sum of $5100 at a rate of 9% simple interest.

(4) Ashley had to pay $4823 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(5) How much loan did Mary borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $6060 to clear it?

(6) Calculate the amount due if Mary borrowed a sum of $3050 at 8% simple interest for 3 years.

(7) How much loan did Kimberly borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $7647.5 to clear it?

(8) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 3% simple interest for 8 years.

(9) Calculate the amount due after 9 years if Barbara borrowed a sum of $5550 at a rate of 5% simple interest.

(10) Joseph had to pay $3922 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.